1. Field of Invention
Various exemplary embodiments of the present invention relate to an electronic device and, more particularly, to a three-dimensionally stacked memory device having memory cells and a method of manufacturing the same.
2. Description of Related Art
A non-volatile memory retains data stored therein even when not powered. Two-dimensional memory devices in which memory cells are fabricated in a single layer over a silicon substrate have reached physical limits in increasing their degree of integration. Accordingly, three-dimensional (3D) non-volatile memory devices in which memory cells are stacked in a vertical direction over a silicon substrate have been proposed.
In a three-dimensional non-volatile memory device, a plurality of word lines may be stacked. Therefore, in order to select a desired word line, among the stacked word lines staked, pad portions are defined in the respective word lines, and contact plugs are coupled to the respective pad portions. Conventionally, pad portions may be defined by patterning the stacked word lines into a stepped structure. However, it is difficult to pattern the word lines into the stepped structure, because of the contact region having a wide area. Therefore, an increase in the degree of integration of a memory device may be difficult.